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Breast tumor characteristics predict likelihood of contralateral breast cancer

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Physicians at The University of Texas M. D. Anderson Cancer Center have identified several characteristics of unilateral malignant breast tumors that are associated with an increased likelihood of cancer in the contralateral breast.

“Defining the risk of contralateral cancer for breast cancer patients may help to reduce the rate of contralateral prophylactic mastectomy,” Dr. Kelly K. Hunt and her associates write in a January 26 online posting by the journal Cancer. The article is slated for print publication in the March 1 issue.

The Houston-based team examined clinical factors and histologic findings from 542 unilateral breast cancer patients who underwent contralateral prophylactic mastectomy. Prior to prophylactic surgery there was no clinical or radiographic evidence of a contralateral breast malignancy.

Examination of the contralateral breast tissue revealed 4.6% with an occult malignancy and 15% with moderate- to high-risk histologic findings (atypical ductal hyperplasia, atypical lobular hyperplasia, and lobular carcinoma in situ).

Multivariate analysis revealed three independent risk factors for malignancy in the contralateral breast: an ipsilateral invasive lobular histology, an ipsilateral multicentric tumor, and a 5-year Gail risk of 1.67% or higher.

“Contralateral prophylactic mastectomy may be a rational choice for breast cancer patients who have a 5-year Gail risk of 1.67% or higher, an additional ipsilateral moderate-risk to high-risk pathology, an ipsilateral multicentric tumor, or an ipsilateral invasive lobular histology,” Dr. Hunt’s team suggests.

However, among patients treated with neoadjuvant chemotherapy, only an ipsilateral invasive lobular histology was associated with contralateral breast cancer, and only an additional ipsilateral moderate- to high-risk pathology was associated with similar histologic findings in the other breast.

Thus, the investigators conclude, “Patients with unilateral breast cancer have options less extreme than contralateral prophylactic mastectomy for risk reduction,” including chemotherapy and endocrine therapy.

Cancer 2009;115.